KR100705272B1 - Apparatus and method for driving electro-luminescence display device - Google Patents

Abstract

The present invention relates to an apparatus and method for driving an electroluminescence display device which improves response speed and reduces power consumption.

In accordance with another aspect of the present invention, a driving apparatus of an electroluminescence display device includes a scan driver for selecting a scan line by supplying a scan signal to one of a plurality of scan lines, and a cross section of the scan lines in synchronization with the scan signal. A data driver for supplying a constant current to a plurality of data lines, and a scan driver and a scan to accumulate a predetermined current for a time except for a time when a scan signal is supplied to accelerate a rise time of a data signal applied to the data line And an inductor portion formed between the signal sources.

Description

Apparatus and method for driving an electroluminescent display device {APPARATUS AND METHOD FOR DRIVING ELECTRO-LUMINESCENCE DISPLAY DEVICE}             

1 is a cross-sectional view schematically showing a conventional organic electroluminescent display device.

2 is a plan view showing an electrode arrangement of a drive device of a conventional organic electroluminescent display device and the organic electroluminescent display device.

3 is a waveform diagram illustrating driving signals output from the driving apparatus illustrated in FIG. 2.

FIG. 4 is a waveform diagram illustrating a delay of data shown in FIG. 3.

5 is a plan view illustrating an electrode arrangement of an organic electroluminescent display device and an organic electroluminescent display device according to an embodiment of the present invention.

6 is a view illustrating in detail the jaw portion of FIG. 5.

FIG. 7 illustrates scan pulses supplied to the scan lines SL1 to SLn shown in FIG. 5, data pulses supplied to the data electrodes DL1 to DLm, and third and fourth switch elements shown in FIG. 6. It is a figure which shows the control signals supplied.

<Description of Symbols for Main Parts of Drawings>

1 glass substrate 2 anode

3: hole injection layer 4: light emitting layer

5: electron injection layer 6: cathode

20,40 Pixel cell 21,41 Constant current source

22, 23, 42, 43, 52, 53: switch element 44: inductor portion

45: timing controller 51: inductor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescent display device, and more particularly, to an apparatus and method for driving an electroluminescent display device with improved response speed and reduced power consumption.

Recently, various flat panel displays have been developed to reduce weight and volume, which are disadvantages of cathode ray tubes. As flat panel displays, liquid crystal displays (hereinafter referred to as "LCDs"), field emission displays (FEDs) and plasma display panels (hereinafter referred to as "PDPs") and electroluminescence (Electro-luminescence: "EL") There are display elements, etc. PDP is most advantageous for large screen because of its relatively simple structure and manufacturing process, but it has the disadvantage of low luminous efficiency, low luminance and high power consumption. Although it is difficult to make a large screen because of the semiconductor process, the demand is increasing as it is mainly used as a display device of a notebook computer, but it is difficult to make a large screen and a power consumption is large due to the backlight unit. The optical elements such as prism sheet, diffuser plate, etc. have the disadvantage of high light loss and narrow viewing angle, whereas EL display elements are classified into inorganic EL and organic EL. The organic EL display device can display an image with a high luminance of tens of thousands of cd / m 2 with a voltage of about 10 [V].

The organic EL display device forms an anode 2 made of a transparent conductive material on the glass substrate 1, as shown in FIG. 1, on which a hole injection layer 3, an organic light emitting layer 4, and an electron injection layer are formed. 5 and a cathode 6 made of metal are laminated. When an electric field is applied between the anode 2 and the cathode 6, holes in the hole injection layer 3 and electrons in the electron injection layer 5 respectively advance toward the light emitting layer 4 and are coupled in the light emitting layer 4. Then, the fluorescent material in the light emitting layer 4 is excited and transitions to generate visible light. At this time, the luminance is not proportional to the voltage between the anode 2 and the cathode 6, but is proportional to the current. Therefore, in general, an apparatus for driving an organic EL display element drives an organic EL display element with a constant current source.

Referring to FIG. 2, a conventional apparatus for driving an organic EL display device scans a constant current source 21 for supplying current to the data lines DL1 to DLm and a scan line for each of the scan lines SL1 to SLn. Switch elements 22 and 23 for supplying a high voltage Vhigh and a ground voltage or ground voltage GND are provided.

The data lines DL1 to DLm serve as cathodes in FIG. 1, and the scan lines SL1 to SLn serve as anodes in FIG. 1. m × n pixel cells 20 are formed at intersections of the m data lines DL1 to DLm and the n scan lines SL1 to SLn. The constant current source 21 is implemented with a current mirror including two or more switch elements and a current source. The constant current source 21 supplies a constant current to the data lines DL1 to DLm in synchronization with the scan pulses supplied to the scan lines SL1 to SLn according to the input data. The switch elements 22 are implemented with transistor elements such as MOS-FETs. The switch elements 22 and 23 connected to the scan lines SL1 to SLn sequentially supply negative scan voltages from the first scan line SL1 to the nth scan line SLn to display data. Select the scan line. To this end, the switch elements 22 connected to the ground voltage source GND are turned on in response to the control signal T1 to supply the ground voltage GND to the selected scan line, and to the scan high voltage source Vhigh. The connected switch elements 23 are turned on in response to the control signal T2 to supply the scan high voltage Vhigh to the unselected scan lines.

3 illustrates a scan pulse supplied to the scan lines SL1 to SLn and a data pulse supplied to the data lines DL1 to DLm.

Referring to FIG. 3, the scan pulse SCAN is sequentially applied to the scan lines SL1 to SLn as a negative voltage, that is, a forward voltage, and the data pulse DATA is synchronized with the scan pulse SCAN. To DL1 to DLm are applied with positive current. In this case, among the pixel cells DATA connected to the scan lines SL1 to SLn to which the negative voltage is applied, only the pixel cells DATA to which the positive current is applied according to data are emitted.

On the other hand, opposite ends of the pixel cells 20 connected to the scan lines SL1 to SLn that are not selected are charged with reverse current. In this state, when a negative voltage is applied to the scan lines SL1 to SLn that are not selected, and the scan lines SL1 to SLn are selected, the pixel cells 20 that are charged in the reverse current are the actual EL of FIG. 4. Charge current flows to a desired positive data current level, such as data RDATA applied to the panel, and consumes a considerable delay time [Delta] t. This is because the input current supplied to the pixel cells 20 charged in the reverse current is consumed by the reverse current.

The data delay of the organic EL display device can be described in more detail through Equation (1). The equivalent capacitance of the pixel cell 20 is C, the voltage charged in the pixel cell 20 is V, the amount of current charged in the pixel cell 20 is Q, and the current input to the pixel cell 20 is I. At this time, the amount of current charged in the pixel cell 20 is determined as in Equation 1 below.

Q = C × V = I × t

If the current is constant over time, the time t for charging the pixel cell 20 to the desired voltage becomes (C × V) / I. For example, when C is 2.4 [nF] and I is 200 [㎂], the time required for the charging flow to fill the flow cell 20 to 10 [V] is (2.4 [nF] × 10 [ V]) / 200 [Hz] = 120 [μsec]. This charging time is considerably longer than the emission time of one scan line in the organic EL display element.

This delay time lowers the effective response speed and luminance of the pixel cells 20. In order to compensate for the decrease in response speed, the current must be high, but this causes another problem of increasing power consumption because the driving voltage of each pixel cell 20 must be increased.

Further, in the conventional drive device of the EL display element, since the data lines DL1 to DLm are driven by the constant current source 21, it is difficult to equalize the luminance between the data lines DL1 to DLm. In order to make the luminance between the data lines DL1 to DLm uniform, the current supplied from the constant current source 21 to each of the data lines DL1 to DLm must be the same. To this end, the current deviation range of a plurality of integrated circuits (hereinafter referred to as "IC") including the constant current source 21 must be minimized. For example, in order to uniformize the luminance of each of the data lines DL1 to DLm to about 20 [nit], the current deviation range of each data driving IC should be limited to within 50 ± 0.5 [kW]. In real circuit implementation, designing and fabricating a data driver IC having a current deviation of less than 1% not only increases the IC cost but also the desired current deviation of each data driver IC even when the driver ICs are applied to an actual EL panel. It is difficult to drive within.

As a result, the conventional EL display element is driven to drive the data lines DL1 to DLn with the constant current source 21, resulting in low luminance and uniformity of luminance, resulting in poor image quality.

Accordingly, it is an object of the present invention to provide an apparatus and method for driving an electroluminescence display device capable of improving the delay of response speed caused by the limitation of the constant current source and reducing the power consumption.

In order to achieve the above object, a driving apparatus of an electroluminescence display device according to an embodiment of the present invention is a scan driver for selecting a scan line by supplying a scan signal to any one of a plurality of scan lines, and the scan A data driver for supplying a constant current to a plurality of data lines intersecting the scan lines in synchronization with a signal, and data that is accumulated in a predetermined current for a time except for a time when the scan signal is supplied and applied to the data lines. And an inductor portion formed between the scan driver and the scan signal supply source to speed up the rise time of the signal.

In the present invention, the inductor unit includes an inductor formed between the scan driver and a scan signal source to accumulate a predetermined current, a first switch element formed between the inductor and a scan signal source to control the inductor, and the scan And a second switch device connected in parallel with the inductor and the first switch device to supply a scan high voltage to a scan line to which a signal is not supplied.

The data driver in the present invention is characterized by including a constant current source for generating the constant current.

In the present invention, the scan driver includes a base voltage source for generating a ground voltage, a third switch element for switching a current path on the scan lines, a voltage source for generating a predetermined scan high voltage, and a scan source on the scan lines. And a fourth switch element for switching the current path.

A method of driving an electroluminescence display device according to an embodiment of the present invention includes accumulating a predetermined current before supplying a scan signal to any one of a plurality of scan lines, and using the predetermined stored current. And selecting a scan line by supplying a scan signal to any one of the plurality of scan lines, and supplying data to a plurality of data lines intersecting the scan lines.

Accumulating the predetermined current in the present invention is characterized by an inductor.

The step of selecting a scan line by supplying a scan signal to any one of the plurality of scan lines by using the predetermined accumulated current in the present invention is based on the current accumulated by the inductor in the previous subframe to the scan signal. And supplying the subtracted scan signal to the scan signal in addition to the predetermined accumulated current, and selecting the scan line as the scan signal.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 5 to 7.

5 is a plan view illustrating an electrode arrangement of an organic electroluminescent display device and an organic electroluminescent display device according to an embodiment of the present invention.

Referring to FIG. 5, an apparatus for driving an organic EL display device according to an exemplary embodiment of the present invention includes a constant current source 41 for supplying current to data lines DL1 through DLm, and scan lines SL1 through. The first and second switch elements 42 and 43 and the scan high voltage source Vhigh and the second switch elements for supplying the scan high voltage Vhigh and the ground voltage or the ground voltage GND to SLn, respectively. The inductor 44 for charging and discharging the current consumed for reverse charging, the first and second switch elements 42 and 43 and the respective switch elements in the inductor 44 It includes a timing controller 45 for controlling the.

In the EL panel, m x n pixel cells 40 are formed at intersections of the m data lines DL1 to DLm and the n scan lines SL1 to SLn. In this case, the data lines DL1 to DLm serve as anodes in FIG. 5, and the scan lines SL1 to SLn serve as cathodes in FIG. 5.

The constant current source 41 is implemented with a current mirror including two or more switch elements and a current source. The constant current source 41 supplies the constant current to the data lines DL1 to DLm in synchronization with the scan pulses supplied to the scan lines SL1 to SLn according to the input data.

The first and second switch elements 42 and 43 are implemented with transistor elements such as MOS-FETs. The first and second switch elements 42 and 43 connected to the scan lines SL1 to SLn sequentially supply a positive scan voltage from the first scan line SL1 to the nth scan line SLn. To select the scanline on which the data is displayed.

To this end, the first switch elements 42 connected to the ground voltage source GND are turned on in response to the control signal T1 to supply the ground voltage GND to the selected scan line, and scan high voltage source Vhigh. The second switch elements 43 connected to) are turned on in response to the control signal T2 to supply the scan high voltage Vhigh to the unselected scan lines. Each of the first and second switch elements 42 and 43 is integrated in a scan driver IC.

The inductor 44 is connected between the scan high voltage Vhigh and the second switch elements 43 to charge the current consumed for reverse charging, and then discharges the charged current during the next data waveform driving to scan high voltage. Minimize the supply of supply power from Vhigh.

The timing controller 45 receives the video data and the vertical / horizontal synchronization signals H and V to control signals necessary for the first and second switch elements 42 and 43 and the switch elements in the inductor 44. (T1, T2, IDT1, IDT2) are generated, and the control signals (T1, T2, IDT1, IDT2) are supplied to the control terminals of the corresponding switch elements.

The driving device and method of the EL according to the present invention are consumed for reverse charging when the data waveform is driven by using the inductor section 44 connected between the scan high voltage source Vhigh and the second switch elements 43. Charge the current. Then, when displaying data by applying the next data waveform, in the scan high voltage Vhigh source, only the current charged in the scan high voltage-inductor portion by the inductor 44 is supplied to the scan lines SL1 through SLn. do. In this way, the organic EL device and method can improve the response speed of the pixel according to the application of voltage and minimize the power consumption.

FIG. 6 is a view showing in detail the inductor unit shown in FIG.

Referring to FIG. 6, the inductor unit 44 includes an inductor 51 connected between the second switch elements 43 and the scan high voltage Vhigh in FIG. 5, and the inductor 51 and the scan high voltage ( Vhigh connected in parallel with the inductor 51 and the third switch element 52 between the third switch element 52 and the second switch element 43 and the scan high voltage Vhigh. A fourth switch element 53 is provided.

The inductor 51 charges a current from the scan high voltage source Vhigh and supplies a charged current to the scan lines SL1 to SLn.

The third switch element 52 is connected in series with the inductor 51 and controls the supply of voltage from the scan high voltage source Vhigh to the inductor 51.

The fourth switch element 53 is connected between the second switch elements 43 shown in FIG. 5 and the scan high voltage source Vhigh to be turned on in response to the control signal IDT2. The scan high voltage Vhigh is supplied to the unselected scan lines SL1 to SLn in association with the two switch elements 43.

FIG. 7 illustrates scan pulses supplied to the scan lines SL1 to SLn shown in FIG. 5, data pulses supplied to the data electrodes DL1 to DLm, and third and fourth switch elements shown in FIG. 6. It is a figure which shows the control signals supplied.

Referring to FIG. 7 in conjunction with FIGS. 5 and 6, the scan pulse SCAN is sequentially applied to the scan lines SL1 to SLn as a positive voltage, that is, a forward voltage, and the data pulse DATA is a scan pulse. In synchronization with the SCAN, the data lines DL1 through DLm are applied with a positive voltage. At this time, the scan pulse SCAN rises with a predetermined slope when a base voltage is applied to the data pulse DATA.

As the control signal IDT1 supplied to the third switch element 52 shown in FIG. 6, the negative signal is first advanced so as to advance by a predetermined time Wt before the time when the scan pulse SCAN and the data pulse DATA are applied. Supplied. After the negative control signal is applied for a predetermined time, the bipolar signal is supplied to the control signal IDT1 supplied to the third switch element 52. Thus, the negative signal and the bipolar signal are repeatedly supplied to the gate of the third switch element 52 for one subframe.

As the control signal IDT2 supplied to the fourth switch element 53 shown in FIG. 6, a control signal IDT1 and a reverse signal are supplied to the third switch element 52, and a rising point of the control signal waveform is provided. It is the same as the time point at which the scan pulse SCAN and the data pulse DATA are applied. That is, the control signal IDT2 supplied to the fourth switch element 53 is a reverse signal to the control signal IDT1 supplied to the third switch element 52 and the control signal supplied to the third switch element 52. The signal IDT1 and the reverse signal are supplied so as to be behind the predetermined time Wt.

Referring to driving through the control signals and the output signals from the driving devices, first, at a time T1 when a high voltage is applied to the data lines DL1 to DLm and the scan lines SL1 to SLn, The third switch element 52 is turned off and the fourth switch element 53 is turned on. In this case, the electric current charged in the organic EL panel becomes the voltage between the cathode and the anode constituting the panel.

In the same state as described above, the third switch element 52 is turned on and the fourth switch element 53 is turned off after a predetermined time Wt. In this state, when the data pulse DATA falls from the high to the low state, the scan pulse SCAN of the scan lines SL1 to SLn connected to the inductor 51 of the inductor 44 is also low ( Low). The scan pulse SCAN dropped to the low level is linearly increased by the control signal IDT1 input to the third switch element 52 in the high state.

Thereafter, the control signal IDT1 input to the third switch element 52 is turned off before the data pulse DATA rises to the high voltage. When the fourth switch element 53 is turned on by the control signal IDT2 in synchronization with the high voltage of the data pulse DATA after a predetermined time Wt from the turn-off time, the scan pulse SCAN is automatically turned high. The current charged in the inductor 51 flows into the scan lines SL1 through SLn while rising to the voltage.

When driving as described above, the data pulse DATA which repeats turn-on / off to be synchronized with the automatically repeated scan pulse SCAN can increase the rise time of the pulse voltage quickly and also improve the power consumption. can do.

As described above, the driving device and method of the EL according to the present invention can increase the rise time of the data pulse signal by forming and driving the inductor portion between the scan high voltage source and the scan line. Thus, the driving device and method of the EL according to the present invention can improve the response speed of the pixel and reduce the power consumption.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (8)

A scan driver for selecting a scan line by supplying a scan signal to any one of the plurality of scan lines; A data driver for supplying a constant current to a plurality of data lines crossing the scan lines in synchronization with the scan signal; And an inductor portion formed between the scan driver and a scan signal supply source to accumulate a predetermined current for a time other than the time for which the scan signal is supplied to accelerate the rise time of the data signal applied to the data line. Driving device of luminescence display element. The method of claim 1, The inductor unit includes an inductor formed between the scan driver and a scan signal source to accumulate a predetermined current; A first switch element formed between the inductor and a scan signal source to control the inductor; And a second switch element connected in parallel with the inductor and the first switch element to supply a scan high voltage to the scan line to which the scan signal is not supplied. The method of claim 1, And the data driver comprises a constant current source for generating the constant current. The method of claim 1, The scan driver may include: a base voltage source for generating a ground voltage, a third switch element for switching a current path on the scan lines; And a fourth switch element for switching a current source on the scan lines and a voltage source for generating a predetermined scan high voltage. Accumulating a predetermined current before supplying a scan signal to any one of the plurality of scan lines; Selecting a scan line by supplying a scan signal to any one of the plurality of scan lines using the predetermined stored current; And supplying data to a plurality of data lines which intersect the scan lines. The method of claim 5, And the accumulation of the predetermined current is performed by an inductor. The method of claim 6, Selecting a scan line by supplying a scan signal to any one of the plurality of scan lines by using the predetermined accumulated current may include scanning a scan signal by subtracting the current accumulated by the inductor in a previous subframe. Supplying the scan signal in addition to the predetermined accumulated current; And selecting the scan line based on the scan signal. The method of claim 7, wherein And the data lines are driven at a constant current.

Images